1. Field of the Invention
The present invention relates to a bidirectional differential clutch which enables to transmit or cutoff both clockwise and counterclockwise rotation at the input side.
2. Description of the Prior Art
An over-running type clutch or a differential clutch which enables to transmit driving force to front wheels automatically a the instant of falling speed due to slip of rear wheels has come to be employed on a part-time type four wheel driving car (hereinafter also referred to as a 4WD car).
In this differential clutch, front wheel hubs are designed to rotate faster than a drive shaft so that the rotation of the drive shaft may not be transmitted to front wheel hubs in driving with two wheels. When rear wheels slip and the rotation of the drive shaft increases, the drive shaft and the front wheel hub come to engagement due to wedge like action of rollers or balls inserted into the clearance of the drive shaft and the front wheel hub, thus the rotation being transmitted to the front wheel hub.
In order to produce this wedge-like action on the differential clutch, the front surface of the drive shaft is provided with a saw tooth like cam. As it operates only in one way rotation, there was a problem that front wheels can not be driven in going backwards. Also in differential clutches using sprags instead of rollers or balls, the operation of sprags was limited to one direction, resulting in the same problem.
The present invention was made to solve the above-described problem and it is an object to provide a bidirectional differential clutch which enables to transmit or cutoff both clockwise and counterclockwise rotation at the input side.